1. Field of the Invention
Exemplary aspects of the present invention generally relate to a clutch mechanism and an image forming apparatus including the clutch mechanism, and more particularly to an image forming apparatus such as a copier, a facsimile machine, a printer, or a multi-functional system including a combination thereof.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile capabilities, typically form an image on a recording medium according to image data. Thus, for example, a charger uniformly charges a surface of an image bearing member (which may, for example, be a photoconductive drum); an optical writer projects a light beam onto the charged surface of the image bearing member to form an electrostatic latent image on the image bearing member according to the image data; a developing device supplies toner to the electrostatic latent image formed on the image bearing member to render the electrostatic latent image visible as a toner image; the toner image is directly transferred from the image bearing member onto a recording medium or is indirectly transferred from the image bearing member onto a recording medium via an intermediate transfer member; a cleaning device then cleans the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the unfixed toner image to fix the unfixed toner image on the recording medium, thus forming the image on the recording medium.
There is demand for low-priced, energy-efficient, compact image forming apparatuses such as copiers, facsimile machines, printers, or multi-functional systems including a combination thereof. Various attempts have been made to reduce the cost and the size of the apparatus. For example, the number of drive sources such as the motors, etc., is reduced, and a planetary gear decelerator is employed to decelerate drive power from the drive sources in limited space.
To reduce consumption of power, clutch mechanisms employing various kinds of planetary gear mechanisms (hereinafter referred to as planetary gear clutch mechanisms) have been proposed. For example, JP-2009-073648-A proposes a combination of a planetary gear decelerator and a clutch mechanism for switching between forward and reverse rotation while achieving overall size reduction. In this configuration, however, in order to transmit torque from an input gear to an output gear, power of two solenoids needs to be regulated to change the direction of rotation of the output gear between forward, backward, and idle, hence complicating control of the device.
In view of the above, there is an unsolved need for a clutch mechanism using a planetary gear mechanism that can accommodate reliably bidirectional rotation of a drive unit disposed downstream from the planetary gear mechanism with ease.